Fermentable Fiber for Functional Foods

The title’s abuse of alliteration is meant to draw attention to an often ignored and misunderstood nutrient category with growing scientific evidence for significant health benefits. Fiber!

Most consumers associate fiber with bowel regularity, an important function of normal body physiology. We all know it’s healthy to be regular but there are more subtle and important roles fiber plays in our health and protection against disease.

Defining Insoluble and Soluble Fibers

Sources of dietary fiber are usually divided into categories of “insoluble” and “soluble” fibers. Both types are present in all plant foods, with varying degrees of each according to a plant’s characteristics. Insoluble refers to the inability to dissolve in water and soluble indicates a fiber source that would readily dissolve in water.

As you will soon see, those definitions are too limiting, especially because soluble fiber undergoes active metabolic processing via fermentation that yields end products with broad, significant health effects.

To conceptualize insoluble and soluble fibers, consider the segments of a plum (or prune). The plum skin is an example of an insoluble fiber source, whereas soluble fiber sources are inside the pulp. Other sources of insoluble fiber include: whole wheat, wheat or corn bran, flax seed lignans, and vegetables like carrots, celery, green beans and potato skins.

One of the most versatile sources of dietary fiber is the husk (hull) of seeds from psyllium grain (Plantago ovata), a fiber source with clinically demonstrated properties of lowering blood cholesterol when it is regularly included in a human diet. Psyllium seed husk is 34% insoluble fiber and 66% soluble fiber, providing an optimal division of both fiber types that make it a valuable food additive.

Fermentable Fiber

The American Association of Cereal Chemists defined soluble fiber this way: “…[T]he edible parts of plants or similar carbohydrates resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the large intestine”.

There are several key words in this statement that inspire analysis and comment for considering fermentable fiber. Let’s break it down.

• “…edible parts of plants…”
o This phrase indicates that all parts of a plant we eat – skin, pulp, seeds, stems, leaves, roots – contain fiber. Both insoluble and soluble sources are in those plant components.

• “…carbohydrates…”
o Complex carbohydrates, such as long-chained sugars also called starch or polysaccharides, are excellent sources of soluble fiber.

• “…resistant to digestion and absorption in the human small intestine…”
o Foods providing nutrients are digested by enzymes and acids in the stomach and small intestine where the nutrients are released and then absorbed through the intestinal wall for transport via the blood throughout the body. A food resistant to this process is undigested, as both insoluble and soluble fibers are. They pass to the large intestine only affected by their absorption of (insoluble fiber) or dissolution in water (soluble fiber).

• “…complete or partial fermentation in the large intestine…”
o The large intestine is comprised mainly of a segment called the colon within which additional nutrient absorption occurs through the process of fermentation. Fermentation occurs by the action of colonic bacteria on the food mass, producing gases and short-chain fatty acids. It is these short-chain fatty acid—butyric, acetic, propionic, and valeric acids—that have such significant health properties.

Short-chain Fatty Acids

Short-chain fatty acids are absorbed through the intestinal wall into portal blood (from the intestine to the liver) that transports them into the general circulation. Particularly butyric acid has extensive physiological actions that promote health effects among which are:

o Stabilizing blood glucose levels by acting on pancreatic insulin release and liver control of glycogen breakdown

o Suppressing cholesterol synthesis by the liver, thereby reducing blood levels of low-density lipids (LDL cholesterol) and triglycerides responsible for atherosclerosis

o Lowering colonic pH (i.e., raise the acidity levels in the colon) which protects the colon lining from cancer polyp formation and increases absorption of minerals such as calcium, magnesium and iron

o Stimulating production of T helper cells, antibodies, leukocytes, splenocyte cytokines and lymph mechanisms having crucial roles in immune protection

o Increasing proliferation of colonic bacteria beneficial for intestinal health—bifidobacteria and lactobacilli (providing a probiotic value)

o Improving barrier properties of the colonic mucosal layer, inhibiting inflammatory and adhesion irritants

To summarize these effects, fermentable fibers yield the important short-chain fatty acids that affect blood glucose and lipid levels. They also improve the colonic environment and regulate immune responses.

Regulatory Guidance on Fiber Products

Americans and Canadians consume less than 50% of the dietary fiber levels required for good health. Recognizing the growing scientific evidence for physiological benefits of increased fiber intake, regulatory agencies such as the US FDA have given approvals to food products making health claims for fiber. In clinical trials to date, these fiber sources were shown to significantly reduce blood cholesterol levels and so are important to cardiovascular health.

The Soluble (fermentable) fiber sources gaining FDA approval are:

o Psyllium seed husk (7 grams per day)
o Beta-glucan from oat bran, whole oats, oatrim or rolled oats (3 grams per day)
o Beta-glucan from whole grain or dry-milled barley (3 grams per day)

Other examples of fermentable fiber sources used in functional foods and supplements include:

o Inulin
o Fructans
o Xanthan gum
o Cellulose
o Guar gum
o Oligofructose
o Oligo- or polysaccharides

Consistent intake of fermentable fiber through foods like berries and other fresh fruit, vegetables, whole grains, seeds and nuts is now known to reduce the risk of some of the world’s most prevalent diseases.

These diseases include:

o Obesity
o Diabetes
o High blood cholesterol
o Cardiovascular disease
o Numerous gastrointestinal disorders (constipation, inflammatory bowel disease, ulcerative colitis, Crohn’s disease, diverticulitis and colon cancer)

 Putting A Stop To Food Cravings

Most of us don’t eat the perfect diet and we have struggles with food, same as everyone else. Having an awareness of this and knowing a little bit about our health and food nutrition can help when it comes to making wise decisions.

Many people struggle with food “cravings.” Studies tell us that it’s fairly common for food cravings to happen quite often at around bedtime. Your guard may be down, you may have had an unusually hard day, and off you go on your not-so-merry way to find that tasty treat.

When food cravings are unconstrained, what starts out as a bedtime snack quickly turns into a full blown feeding frenzy. We head to the kitchen and every other place where food can hide, clearing a path as we go.

Most food cravings are not about satisfying a nutritional need or imbalance. They seem to be more emotionally related, or God forbid, are caused by plain old gluttony. Exactly why we over-indulge is not completely understood.

Listed below are some thoughts and ideas about food cravings:

- If the food isn’t available, you can’t eat it! Empty the cookie jar and keep it that way! Keep healthy food choices on-hand.

- Recognize the feelings and emotions that lead-up to a food craving. Do you have food cravings when you’re bored, lonely, or stressed? If you can identify a trigger, you can deal with the emotion that’s making you desire a certain food.

- Don’t beat yourself-up. There is always tomorrow. Call a friend, make good use of your support network and share your feelings with someone.

- Get enough sleep. When you’re tired, you’re more likely to crave things.

- Never give-up. When you “slip”, do whatever is necessary to re-gain control. Try to practice restraint most of the time,

Think moderation and not abstinence at all times!

- Understand that self-control and discipline by themselves, won’t cut it! If you depend totally on yourself for control, you will fail. Forming caring and supportive relationships is required. If you do not currently have a support network, start building one TODAY.

- Exercise. It increases feel-good endorphins that cut down on your cravings. Try to get at least 30 minutes of physical activity every day.

- Use moderation. Instead of stuffing yourself with every kind of food hoping that your craving will go away, eat 100 to 200 calories of your “craved” food.

- Substitute with low-fat foods and complex carbs. If you’re hungry for chocolate, eat non-fat chocolate yogurt. Try fig bars or raisins for a sweet craving.

- Never skip a meal. Eat every three to five hours. Try six smaller meals or regular meals with nutritious snacks.

- Understand that hunger cravings are oftentimes stress related; walk in the park, spiritual connections, a cozy fireplace, baths…all these stimulate regions of the brain that stimulate pleasure. Relaxation techniques may also work. Bottom line, substitute pleasurable experiences for comfort foods.

- Beware of certain medications. They can stimulate appetite. Drugs used for the treatment of depression and bipolar disorder can be appetite stimulants. Other drugs, both prescription and over the counter, may influence appetite as well. If you are on a medication, and troubled by food cravings, discuss this with your doctor or pharmacist. You may be able to find an alternative that doesn’t send your cravings out of control.

- Distract Yourself. Get busy. Do anything other than cave-in to your desire for food.

- Look inside your refrigerator and kitchen cabinets and do some “house cleaning.” Throw-out that unhealthy stuff and start shopping more wisely. Careful planning will go a long way for improving your chances of success.